Correlation of serological markers and platelet count in the diagnosis of Dengue virus infection

BACKGROUND: The dengue virus causes one of the most important mosquito-borne viral diseases. Annually, it affects up to 100 million people. Detection of the secreted NS1 protein represents a new approach to the diagnosis of acute dengue infection. Platelet count is the only non-dengue parameter that can support the diagnosis of the dengue shock syndrome (DSS) and dengue hemorrhagic fever (DHF). This study was done to correlate the platelet count and dengue parameters detected by the immunochromatographic test (ICT). MATERIALS AND METHODS: Serum samples collected from patients presenting with dengue-like illness and for whom an anti-dengue antibody test was requested between August 2010 and August 2012, were included in this study. A total of 520 serum samples were collected from the suspected dengue fever patients. The samples were tested for NS1 antigen, IgM, and IgG antibodies, using the ICT kit. The platelet count was recorded in dengue parameter-positive and -negative cases. RESULTS: A total of 520 serum samples were collected from the suspected dengue fever patients. Sixty-two samples tested positive for one or more dengue-specific parameters. Out of the 62 samples, 39 (62.9%) were positive for the NS1 antigen, only seven (11.3%) were positive for IgM, and only three (4.9%) were positive for IgG. A platelet count < 1,00,000/ml was observed in 32 cases (51.6%). When the platelet count was done in 100 dengue parameter-negative fever patients (controls), thrombocytopenia was observed in 30% of the cases. CONCLUSION: Association of thrombocytopenia in dengue parameter-positive cases was highly significant (Z = 2.76, P = 0.006) when compared to thrombocytopenia in dengue parameter-negative patients.